add city damange value

src/entity/City.ts

@@ -4,6 +4,8 @@ import { CityEvent, CityEventType, CityInitializedEvent } from "./CityEvent";
 type EventHandler<T extends CityEvent> = (event: T) => void;
 
 export class City {
+	static readonly MAX_DAMAGE = 100;
+
 	private _events: CityEvent[] = [];
 
 	constructor(public readonly id: string) {
@@ -21,6 +23,14 @@ export class City {
 		this._events.push(event);
 	}
 
+	public get damage(): number {
+		return 0;
+	}
+
+	public get isDestroyed(): boolean {
+		return this.damage >= City.MAX_DAMAGE;
+	}
+
 	public get events(): CityEvent[] {
 		return this._events.map((event) => ({ ...event }) as CityEvent);
 	}

src/usecase/CitySnapshotUsecase.ts

@@ -2,6 +2,8 @@ import { CityRepository } from "./interface";
 
 export type CitySnapshot = {
 	id: string;
+	damage: number;
+	isDestroyed: boolean;
 };
 
 export class CitySnapshotUsecase {
@@ -15,6 +17,8 @@ export class CitySnapshotUsecase {
 
 		return {
 			id: city.id,
+			damage: city.damage,
+			isDestroyed: city.isDestroyed,
 		};
 	}
 }